Charge injection and transport layers

ABSTRACT

Compositions for use in hole transporting layers (HTLs) or hole injection layers (HILs) are provided, as well as methods of making the compositions and devices fabricated from the compositions. OLED devices can be made. The compositions comprise at least one conductive conjugated polymer, at least one semiconducting matrix component that is different from the conductive conjugated polymer, and an optional dopant, and are substantially free of an insulating matrix component.

RELATED APPLICATIONS

This application claims priority to U.S. provisional application Ser.No. 61/108,844 filed Oct. 27, 2008 to Mathai et al., which is herebyincorporated by reference in its entirety.

BACKGROUND

Although useful advances are being made in organic electronic devicessuch as organic photovoltaic devices (OPVs) and organicelectroluminescent devices (including organic light emitting diodes(OLEDs), polymer light emitting diodes (PLEDs), and phosphorescentorganic light emitting diodes (PHOLEDs)), further improvements areneeded in the processing, manufacture and performance these devices. Inparticular, improvements in technologies for hole injection and/or holetransport in these devices is especially desirable. State of the artorganic electronic devices generally still can use hole injection layers(HILs) and/or hole transport layers (HTLs) within the device to optimizecharge flow through the device, separation, or recombination ofelectrons and holes. Hole injection layers and hole transport layers canpresent difficult problems because of the solubilities of the componentmaterials (or lack their of) in processing solvents, and because of thedopants and/or acids needed for HIL or HTL performance. Dopants andacids should be chosen judicially to minimize their contributions todevice degradation.

A need exists for improved hole injection and charge transport materialsthat can enhance the performance of organic electronic devices,producing increased efficiencies, brightness and lifetimes. A need alsoexists for improved hole injection and transport materials that can beadapted for different applications and can function with a variety ofdifferent light emitting layers, photoactive layers, and electrodes.

SUMMARY

Compositions for use in hole transporting layers (HTLs) or holeinjection layers (HILs) are provided, as well as methods of making andusing the compositions and devices fabricated from the compositions.

The compositions can comprise at least one conductive conjugatedpolymer, at least one semiconducting matrix component that is differentfrom the conductive conjugated polymer, and an optional dopant, and canbe substantially free of an insulating matrix component. Thecompositions can produce improved HILs and HTLs that, when incorporatedinto electronic devices such as OLEDs or OPVs, can lead to increases inthe performance of the devices.

Thus, in some aspects, a composition is provided comprising (a) at leastone conductive conjugated polymer, (b) at least one semiconductingmatrix component that is different from the conductive conjugatedpolymer in (a), and (c) optionally, at least one dopant, wherein thecomposition is substantially free of an insulating matrix component.

In other aspects, a composition is provided comprising (a) at least oneconductive conjugated polymer; (b) at least one semiconducting matrixcomponent that is different from the conductive conjugated polymer in(a); (c) a solvent; and (d) optionally, at least one dopant; wherein thecomposition is substantially free of an insulating matrix component.

In some aspects, a method is provided for preparing a composition, themethod comprising: (a) combining the conductive conjugated polymer, thedopant, and the solvent to form a doped conductive polymer solution; and(b) adding the semiconducting matrix component to the doped conductivepolymer solution to form the composition.

In some aspects, a device is provided comprising a hole transport layeror a hole injection layer comprising: (a) at least one conductiveconjugated polymer; (b) at least one semiconducting matrix componentthat is different from the conductive conjugated polymer in (a); and (c)optionally, at least one dopant; wherein the hole transport layer or ahole injection layer is substantially free of an insulating matrixcomponent.

In yet other aspects, a method is provided for improving the efficiencyof an organic electronic device, the method comprising: providing a holetransport layer or hole injection layer comprising (a) at least oneconductive conjugated polymer, (b) at least one semiconducting matrixcomponent that is different from the conductive conjugated polymer in(a), and (c) optionally, at least one dopant, wherein the hole transportlayer or hole injection layer is substantially free of an insulatingmatrix component; and incorporating the hole transport layer or holeinjection layer into the organic electronic device; whereinincorporation of the hole transport layer or hole injection layer intothe organic electronic device leads to an increase in device efficiencyof at least 5%.

At least one advantage for at least one embodiment is improved devicelifetime.

At least one advantage for at least one embodiment is improvedcombinations of device properties, including device performance and/ordevice lifetime.

At least one additional advantage for at least one embodiment isimproved formulation flexibility.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 presents UV-vis-NIR absorbance spectra of the five HIL inkformulations of Example 1.

DETAILED DESCRIPTION Introduction

All references cited herein are incorporated by reference in theirentireties.

The compositions provided herein can comprise at least one conductiveconjugated polymer, at least one semiconducting matrix component that isdifferent from the conductive conjugated polymer in (a), and an optionaldopant, and are substantially free of an insulating matrix component.The compositions can be used to form improved HTLs or HILs that, whenincorporated into electronic devices such as OLEDs or OPVs, result inincreased device performance. For example, the compositions include inkformulations that can be used to form HILs in OLEDs. OLEDs constructedwith the compositions can exhibit increases in efficiency andbrightness. The present compositions thus can provide an improved holeinjection technology that can be used in applications involving organicelectroluminescence, in particular, in OLEDs and other lighting displaysand/or applications.

In the compositions, the conductive conjugated polymer and thesemiconductive matrix component are typically in admixture with oneanother, forming a blended composition that, when present as either anHIL or HTL layer in a device, permits charge injection to take placethroughout the bulk of the layer rather than at the surface of thelayer.

The compositions can also contain a dopant that functions as a dopingagent for either the conductive or the semiconducting polymer or both.Doping of both the conductive and semiconducting polymers enables rapidcharge transport through the bulk of the present compositions whenincorporated into an organic electronic device, increasing theperformance of the device. The highly conductive doped polymers of thecompositions produce HILs or HTLs having high conductivities, whichlower the series resistance of organic electronic devices. This is incontrast to other hole injection technologies which produce HILs or HTLshaving much lower conductivities (and, as a consequence, devices withhigher series resistance).

In some embodiments, the compositions produce HILs or HTLs that aresubstantially transparent to visible light, even if the thickness of thelayer is higher than usual, for example, on the order of 60 nm to 200nm. For example, the HIL or HTL can transmit about 85% to about 90% orgreater (i.e., % T>85-90%) of light having a wavelength of about 400-800nm. Thus, an additional advantage of the present compositions can be theformation of substantially transparent HILs or HTLs having moderatelyhigh thicknesses. Thick HILs or HTLs can also be used to eliminateshorts in semiconductor devices without adversely impacting operatingvoltage.

Insulating Matrix Component

Traditionally, organic electronic devices such as OLEDs are fabricatedusing HILs or HTLs containing a conductive polymer and one or moreinsulating polymers, such as polystyrene sulfonic acid (PSS) and nafion.Insulating polymers are typically used as the matrix component in HILsor HTLs, forming form the bulk of these layers. Examples of insulatingpolymers that can be used as HIL/HTL matrix components includepoly(styrene) or poly(styrene) derivatives, poly(vinyl acetate) or itsderivatives, poly(ethylene glycol) or its derivatives,poly(ethylene-co-vinyl acetate), poly(pyrrolidone) or its derivatives(e.g., poly(1-vinylpyrrolidone-co-vinyl acetate)), poly(vinyl pyridine)or its derivatives, poly(methyl methacrylate) or its derivatives,poly(butyl acrylate) or its derivatives. The use of insulating polymersin HILs or HTLs are described more fully in U.S. Pat. Appl. Publ. No.2006/0175582, by Hammond et al. Insulating polymers typically possess aband gap greater than 3 eV.

In contrast, the semiconducting matrix component of the presentinvention is used in place of the insulating polymer matrix component oftraditional HILs or HTLs. The present compositions are substantiallyfree of an insulating matrix component. Typically, the presentcompositions contain less than about 5% (w/w), less than about 3% (w/w),less than about 2% (w/w), less than about 1% (w/w), less than about 0.5%(w/w), less than about 0.25% (w/w), less than about 0.1% (w/w), lessthan about 0.01% (w/w), or less than about 0.001% (w/w) of an insulatingmatrix component. Weight percentages are calculated on the basis of theweight of all solids in the composition.

For example, when in the form of ink formulations, the presentcompositions typically contain less than about 3% (w/w), less than about2% (w/w), less than about 1% (w/w), or less than about 0.5% (w/w) of aninsulating matrix component. Typically, an ink formulation can containfrom about 0.5% (w/w) to about 3.0% (w/w), about 0.5% (w/w) to about2.0% (w/w), about 0.5% (w/w) to about 1.0% (w/w) of an insulating matrixcomponent.

Conductive Conjugated Polymers

The present compositions comprise at least one conductive conjugatedpolymer.

Electrically conductive conjugated polymers and their use in organicelectronic devices are known in the art. See, for example, Friend,“Polymer LEDs,” Physics World, November 1992, 5, 11, 42-46. See alsoKraft et al., “Electroluminescent Conjugated Polymers-Seeing Polymers ina New Light,” Angew. Chem. Int. Ed. 1998, 37, 402-428.

Electrically conductive conjugated polymers are also described in TheEncyclopedia of Polymer Science and Engineering, Wiley, 1990, pages298-300, which is hereby incorporated by reference in its entirety. Thisreference describes conductive conjugated polymers, includingpolyacetylene, poly(p-phenylene), poly(p-phenylene sulfide),polypyrrole, and polythiophene, as well as blending and copolymerizationof polymers, including block copolymer formation, and disclosesconductive conjugated polymers that can be used in the presentcompositions. See also Groenendaal et al., Adv. Materials 15:855-879(2003); Patil et al., Chem. Rev. 88:183-200 (1988); Roncali, J., Chem.Rev. 97:173-205 (1997); and Yamamoto and Hayashida, Reactive &Functional Polymers 37:1-17 (1998).

Examples of conductive conjugated polymers suitable for use in thepresent compositions also include those disclosed in, e.g., Seshadri,V., and Sotzing, G., “Progress in Optically Transparent ConductingPolymers,” Chpt. 22, in Organic Photovoltaics, Sun and Sariciftci, eds.,CRC Press, 2005, pp. 495-527.

In some embodiments, the conductive polymer comprises a conductiveheterocyclic conjugated polymer. Suitable heterocyclic conjugatedpolymers include, for example, polythiophene polymers. Conductiveheterocyclic conjugated polymers suitable for use in the presentformulations and devices can be obtained from Plextronics, Inc.,Pittsburgh, Pa., including, for example, polythiophene-based polymerssuch as Plexcore® and similar materials.

Polythiophenes are described, for example, in Roncali, J., Chem. Rev.1992, 92, 711; Schopf et al., Polythiophenes: Electrically ConductivePolymers, Springer: Berlin, 1997. See also for example U.S. Pat. Nos.4,737,557 and 4,909,959. In addition, synthetic methods, doping, andpolymer characterization, including regioregular polythiophenes withside groups, is provided in, for example, U.S. Pat. Nos. 6,602,974 toMcCullough et al. and 6,166,172 to McCullough et al., which are herebyincorporated by reference in their entireties. Additional descriptioncan be found in the article, “The Chemistry of ConductingPolythiophenes,” by Richard D. McCullough, Adv. Mater. 1998, 10, No. 2,pages 93-116, and references cited therein, which is hereby incorporatedby reference in its entirety. Another reference which one skilled in theart can use is the Handbook of Conducting Polymers, 2^(nd) Ed. 1998,Chapter 9, by McCullough et al., “Regioregular, Head-to-Tail CoupledPoly(3-alkylthiophene) and its Derivatives,” pages 225-258, which ishereby incorporated by reference in its entirety. This reference alsodescribes, in chapter 29, “Electroluminescence in Conjugated Polymers”at pages 823-846, which is hereby incorporated by reference in itsentirety. Polymeric semiconductors are described in, for example,“Organic Transistor Semiconductors” by Katz et al., Accounts of ChemicalResearch, vol. 34, no. 5, 2001, page 359 including pages 365-367, whichis hereby incorporated by reference in its entirety.

Conductive conjugated polymers suitable for use in the presentcompositions can be in the form of homopolymers, copolymers, or blockcopolymers. Block copolymers are described in, for example, BlockCopolymers, Overview and Critical Survey, by Noshay and McGrath,Academic Press, 1977. For example, this text describes A-B diblockcopolymers (chapter 5), A-B-A triblock copolymers (chapter 6), and-(AB)_(n)-multiblock copolymers (chapter 7), which can form the basis ofblock copolymer types as described herein. Additional block copolymers,including polythiophenes, are also described in, for example, Francoiset al., Synth. Met. 1995, 69, 463-466, which is incorporated byreference in its entirety; Yang et al., Macromolecules 1993, 26,1188-1190; Widawski et al., Nature (London), vol. 369, Jun. 2, 1994,387-389; Jenekhe et al., Science, 279, Mar. 20, 1998, 1903-1907; Wang etal., J. Am. Chem. Soc. 2000, 122, 6855-6861; Li et al., Macromolecules1999, 32, 3034-3044; and Hempenius et al., J. Am. Chem. Soc. 1998, 120,2798-2804.

In some embodiments, the conductive conjugated polymer comprises aregioregular conjugated polymer. In particular, the conductiveconjugated polymer can comprise a heterocyclic conjugated polymer thatis regioregular, including, for example, a regioregular polythiophenepolymer.

Regioregularity can arise in multiple ways. For example, it can arisefrom polymerization of asymmetric monomers such as a 3-alkylthiophene toprovide a head-to-tail (HT) poly(3-substituted)thiophene. Alternatively,it can arise from polymerization of monomers which have a plane ofsymmetry between two portions of monomer, such as, for example, abi-thiophene, providing, for example, regioregular HH-TT and TT-HHpoly(3-substituted)thiophenes.

The following article describes several types of regioregular systemsbeginning at page 97 and references cited therein: “The Chemistry ofConducting Polythiophenes,” by Richard D. McCullough, Adv. Mater. 1998,10, No. 2, pages 93-116. In a regioregular polymer, including apolythiophene derivative, the degree of regioregularity can be, forexample, about 90% or more, or about 95% or more, or about 98% or more,or about 99% or more. Methods known in the art such as, for example, NMRcan be used to measure the degree of regioregularity. In someembodiments, the degree of regioregularity is greater than about 75%. Inother embodiments, the degree of regioregularity is between about 85%and 100%.

In other embodiments, the conductive conjugated polymer comprises aheterocyclic conjugated polymer that is relatively regioirregular. Forexample, the degree of regioregularity can be about 90% or less, orabout 80% or less, or about 70% or less, or about 60% or less, or about50% or less.

Polythiophene polymers suitable for use in the present compositions anddevices can also be star shaped polymers, with the number of branchesbeing, for example, more than three and comprising thiophene units.Polythiophene polymers can also be dendrimers. See, for example,Anthopoulos et al., Applied Physics Letters, 82, 26, Jun. 30, 2003,4824-4826.

In some embodiments, the conductive conjugated polymer comprises aregioregular 3-substituted polythiophene, including, for example, aregioregular HH-TT or TT-HH poly(3-substituted)thiophene such as a HH-TTor TT-HH poly(3-polyether)thiophene. Examples of conductive conjugatedpolymers suitable for use in the present compositions are described inU.S. provisional Appl. No. 61/044,380, filed Apr. 11, 2008, by Seshadriet al., entitled “Doped Conjugated Polymers, Devices, and Methods ofMaking Devices,” (and also U.S. patent application Ser. No. 12/422,159filed Apr. 10, 2009), which are herein incorporated by reference intheir entirety. Additional examples of suitable conductive conjugatedpolymers are described in Williams et al., U.S. provisional Appl. No.61/043,654, filed on Apr. 9, 2008, by Williams et al., entitled “Holecollection Layer Compositions and Photovoltaic Devices”; U.S. Pat. Publ.No. 2006/0175582 A1, by Hammond et al., entitled “HoleInjection/Transport Layer Compositions and Devices”; U.S. Pat. Publ. No.2008/0216894 A1 by T. Hammond, entitled “Quantum Dot PhotovoltaicDevice”; and in Marks et al., U.S. Patent Application Pub. No.2005/0147846 A1. Each of these patent applications and publications ishereby incorporated by reference in its entirety.

For example, in some embodiments of the present compositions, theconductive conjugated polymer comprises a 3,4-disubstitutedpolythiophene, including, for example, a poly(3,4-dialkoxythiophene) ora poly(3,4-di-polyether)-thiophene. 3,4-disubstituted polythiophenessuitable for use in the present compositions, and methods of synthesisand use in electronic devices, are described in U.S. provisional Appl.No. 61/044,380, filed Apr. 11, 2008, by Seshadri et al., as describedabove.

Examples of poly(3,4-dialkoxy)thiophenes andpoly(3,4-di-polyether)-thiophenes include, but are not limited to,poly(3,4-bis(2-(2-butoxyethoxy)ethoxy)thiophene)-2,5-diyl,poly(3,4-bis(2-(2-ethoxyethoxy)ethoxy)thiophene)-2,5-diyl;poly(3,4-bis(2-(2-methoxyethoxy)ethoxy)thiophene)-2,5-diyl;poly(3,4-bis(2-(2-butoxyethoxy)ethoxy)thiophene)-2,5-diyl;poly(3,4-bis(2-(2-butoxybutoxy)butoxy)thiophene)-2,5-diyl; andpoly(3,4-bis(2-(2-methoxymethoxy)methoxy)thiophene)-2,5-diyl.

For example, in some embodiments, the conductive polymer comprisespoly(3,4-bis(2-(2-butoxyethoxy)ethoxy)thiophene (PDBEETh), representedby:

The degree of polymerization n of the conductive conjugated polymer isnot particularly limited, but can be, for example, 2 to 500,000 or 5 to100,000 or 10 to 10,000, or 10 to 1,000, or to 100. In some embodiments,the conductive polymer has a number average molecular weight betweenapproximately 5,000 and 100,000 g/mol.

The conductive conjugated polymer can be in either the neutral oroxidized state, and is typically soluble and/or dispersible in anorganic solvent. For example, in some embodiments, the conjugatedpolymer is soluble in tetrahydrofuran (THF), chloroform, acetonitrile,cyclohexanone, anisole, chlorobenzene, o-dichlorobenzene, ethyl benzoateand mixtures thereof. Thus, in some embodiments, the conductiveconjugated polymer is in a non-aqueous formulation.

In other embodiments, the conductive conjugated polymer is in an aqueousformulation. Examples of such aqueous formulations include aqueousformulations of sulfonated polythiophenes as the conductive conjugatedpolymers. See, e.g., U.S. Pat. Publ. No. 2008/0248313, by Seshadri etal., entitled “Sulfonation of Conducting Polymers and OLED,Photovoltaic, and ESD Devices,” which is incorporated by referenceherein in its entirety. Self-doped conductive conjugated polymers arealso contemplated for the present compositions.

Additional embodiments are described in, for example, (i) U.S.provisional application Ser. No. 61/108,851 filed Oct. 27, 2008; and(ii) U.S. provisional application Ser. No. 61/115,877 filed Nov. 18,2008.

In the present compositions, the conductive conjugated polymer upondoping typically possesses a band gap less than 1 eV or essentially noband gap.

The conductive conjugated polymer may also be a semiconductive polymer,as described below, that has been doped to provide for an effective bandgap or about 0 eV.

Semiconducting Matrix Component

The present compositions also comprise at least one semiconductingmatrix component. The semiconducting matrix component is different fromthe conductive conjugated polymer in the compositions.

The semiconducting matrix component can be a semiconducting smallmolecule, such as a hole transporting compound, or a semiconductingpolymer that is typically comprised of repeat units comprising holetransporting units in the main-chain and/or in a side-chain. Thesemiconducting matrix component may be in the neutral form or may bedoped, and is typically soluble in organic solvents, such as toluene,chloroform, THF, acetonitrile, cyclohexanone, anisole, chlorobenzene,o-dichlorobenzene, ethyl benzoate and mixtures thereof.

Examples of semiconducting small molecules and polymers suitable for useas matrix components are described by Marks et al., in U.S. PatentApplication Pub. No. 2005/0147846 A1, entitled “Hole Transport LayerCompositions and Related Diode Devices,” which is hereby incorporated byreference in its entirety.

Examples of small molecules suitable as for use as the semiconductingmatrix component include, but are not limited to, hole transportingcompounds. Suitable hole transporting compounds, include, for example,triarylamines. Examples of useful triarylamines include1,4-bis(diphenylamino)benzene, represented by:

N—N′-bis(3-methylphenyl)-N—N′-bis(phenyl)benzidine (TPD), representedby:

N—N′-bis(4-methylphenyl)-N—N′-bis(phenyl)benzidine, represented by:

N—N′-bis(2-naphthalenyl)-N—N′-bis(phenyl)benzidine, represented by:

1,3,5-tris(3-methyldiphenyl amino)benzene, represented by:

and1,3,5-tris[(3-methylphenyl)phenylamino]benzene, represented by:

Other suitable hole transporting compounds that can be used assemiconducting matrix compounds include, but are not limited to,tri-p-tolylamine, represented by:

N—N′-bis(1-naphthalenyl)-N—N′-bis(phenyl)benzidine (NPB), representedby:

4,4′,4″-tris(N—N-phenyl-3-methylphenylamino)triphenylamine, representedby:

1,3,5-tris(diphenylamino)benzene, represented by:

N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine, represented by:

4-(diethylamino)benzaldehyde diphenylhydrazone, represented by:

4-(dimethylamino)benzaldehyde diphenylhydrazone, represented by:

4-(dimethylamino)benzaldehyde diphenylhydrazone, represented by:

4-(diphenylamino)benzaldehyde diphenylhydrazone, represented by:

4-(dibenzylamino)benzaldehyde-N,N-diphenylhydrazone, represented by:

andtris[4-(diethylamino)phenyl]amine, represented by:

Additional suitable hole transporting compounds include those based on,or comprising, one or more carbazole units, such as, for example,tris(4-carbazoyl-9-ylphenyl)amine (TCTA);4,4′-bis(carbazol-9-yl)-1,1′-biphenyl (CBP, or4,4′,N,N′-diphenylcarbazole), represented by:

9-ethyl-3-carbazolecarboxaldehyde diphenylhydrazone, represented by:

1,3,5-tris(2-(9-ethylcabazyl-3)ethylene)benzene, represented by:

and tris(4-carbazoyl-9-ylphenyl)amine, represented by:

Other suitable semiconducting matrix compounds include porphyrinic metalcomplexes, such as, for example, copper(II) phthalocyanine, representedby:

andtitanyl phthalocyanine, represented by:

Other small molecules suitable as for use as the semiconducting matrixcomponent include polycyclic aromatic compounds such as anthracene,naphthalene, and fluorene.

The semiconducting matrix component can also comprise a polymer havingone or more repeat units comprising a semiconducting small molecule suchas, for example, a hole transport compound, or a polymer having one ormore repeat units comprising one of the semiconducting small moleculesdescribed above.

Such polymers include, for example, polymers comprised of repeat unitscomprising hole transporting compound units in the main-chain and/or ina side-chain, such as poly-TPD,poly-N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (poly-NPD),polyvinylcarbazole (PVK), and similar polymers.

Additional examples of suitable polymers include the polyarylamineketone polymers disclosed in U.S. Provisional Appl. No. 61/108,851,entitled “Polyarylamine Ketones,” by Seshadri et al., filed on Oct. 27,2008, which is herein incorporated by reference in its entirety. Seealso, U.S. provisional 61/115,877 filed Nov. 18, 2008.

Also suitable are polymers having one or more repeat units comprisingpolycyclic aromatic compound units in the main-chain and/or in aside-chain, including, for example, polyaromatic polymers or polyvinylaromatic polymers such as polyvinyl naphthalene, polyvinyl anthracene,polyanthracene, or fluorene-based polymers.

Examples of suitable fluorene-based polymers include, but are notlimited to,poly[(9,9-dihexylfluorenyl-2,7-diyl)-co-(N—N′-bis{p-butylphenyl}-1,4-diamino-phenylene)],sold by American Dye Source, Inc. (Baie D'Urfe, Quebec, Canada) asADS250BE, represented by:

andpoly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(N—N′-bis{4-butylphenyl}-1,1′-byphenylene-4,4-diamine)],represented by:

Examples of additional polymers suitable for use as the semiconductingmatrix polymer includepoly(N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzedine, represented by:

andpoly(copper phthalocyanine), represented by:

In the present compositions, the semiconducting matrix componenttypically possesses a band gap of less than 3 eV, e.g., a band gap fromabout 1 eV to about 3 eV.

Dopants

The present compositions optionally comprise one or more dopants.

Dopants are typically used to obtain a desired conductive state for apolymer component of an HIL or HTL and often result in improved deviceperformance. For example, upon oxidation of a conjugated conductivepolymer by a redox dopant, electrons are removed from the valence bandof the conductive polymer. This change in oxidation state results in theformation of new energy states for the polymer. The energy levels areaccessible to some of the remaining electrons in the valence band,allowing the polymer to function as a conductor.

In the present compositions, in particular, the conductive conjugatedpolymer can be doped with a redox dopant. Examples of suitable redoxdopants that are known in the art include, but are not limited to,quinones, boranes, carbocations, bora-tetraazapentalenes, aminium orammonilium salts, sulfonium salts, oxonium salts, selenonoium salts,nitrosonium salts, arsonium salts, phosphonium salts, iodonium salts,select metal (e.g. silver) salts, or combinations thereof. Suitableredox dopants include, but not limited to, those disclosed in U.S. Pat.Nos. 5,853,906 and 5,968,674, which are hereby incorporated by referencein their entireties.

The redox dopant can also be selected to provide a suitable chargebalancing counter-anion. The type of dopant anion can affect the dopinglevel of the conductive polymer and the device performance for devicesprepared from these solutions.

The size of the dopant anion can be an important parameter for enhancingthe efficiency of a device. The anion can be a borate anion, ahexafluorophosphate anion, antimoniate, a sulfonate anion, a chlorideanion, a bromide anion, an iodide anion, a tetrafluoroborate anion, ahexafluorophosphate anion, an optionally substituted arylsulfonateanion, an optionally substituted alkylsulfonate anion, aperfluoroalkylsulfonate anion, an optionally substituted tetraarylborateanion, or an optionally substituted tetraalkylborate anion.

In the final compositions, the composition can be distinctly differentfrom the combination of original components (i.e., conductive polymerand/or redox dopant may or may not be present in the final compositionin the same form before mixing). Thus, the conductive conjugated polymerand the dopant, or redox dopant, can refer to components that will reactto form a doped conductive conjugated polymer. In addition, someembodiments allow for removal of reaction byproducts from the dopingprocess. For example, the iodonium redox dopant can result in organicbyproducts that can be washed away from the doped polymer.

In some embodiments, the redox dopant is a photoacid. Examples ofsuitable photoacids include, but are not limited to, onium salts such assulfonium and iodonium salts, for example, as described in Journal ofPolymer Science Part A, Polymer Chem. 37, 4241-4254, 1999, herebyincorporated by reference in its entirety.

Iodonium salts are known in the art. Doping of a conductive polymer,such as a neutral polythiophene, can be achieved using photoacids suchas iodonium salts or diaryl iodonium salts, and in particular, diphenyliodonium salts. The aryl groups such as a phenyl group in the iodoniumsalt can be optionally substituted as known in the art. For example, theredox dopant may be a lipophilic iodonium salt. Typically, the iodoniumsalt is represented by:

wherein independently R₁ is an optionally substituted aryl group,independently R₂ is an optionally substituted aryl group, and X⁻ is ananion.

Doping of a neutral polythiophene can also be achieved using a photoacidsuch as a sulfonium salt. Sulfonium salts are known in the art. The arylgroups in the sulfonium salt can be optionally substituted as known inthe art. Typically, the sulfonium salt is represented by:

wherein independently R₁ is an optionally substituted arene,independently R₂ is a optionally substituted arene, R₃ is a optionallysubstituted arene, and X⁻ is an anion.

The dopant can comprise an optionally substituted diphenyl iodonium saltwith a molecular weight of, for example, about 100 g/mol to about 500g/mol, or approximately 300 g/mol.

In some embodiments, the dopant is the photoacid4-isopropyl-4′-methyldiphenyliodonium tetrakis(pentafluorophenylborate)(IMDPIB(PhF₅)₄), represented by:

Examples of other iodonium salts that may be used, include, but are notlimited to, diphenyliodonium hexafluorophosphate (DPIPF₆),diphenyliodonium para-toluene sulfonate (DPITos),bis-(4-tert-butylphenyl) iodonium trifluoromethane sulfonate(^(t)BDPITFSO₃), and diphenyliodonium perfluoro-1-butane sulfonate(DPIPFBSO₃). The iodonium salt can be a low molecular weight compound orit can be coupled to a high molecular compound such as a polymer.

The redox dopant may be a sulphonium salt. Examples of suitablesulphonium salts include, but are not limited to, triphenylsulphoniumhexafluorophosphate, triphenylsulphonium para-toluene sulfonate,bis-(4-tert-butylphenyl)sulphonium trifluoromethane sulfonate, anddiphenylsulphonium perfluoro-1-butane sulfonate.

Other onium salts may be used provided such that effective doping can beachieved for select counterions.

Another class of dopants that can be used includes quinones. Examples ofsuitable quinones that may be used to effect doping include, but are notlimited to, tetrafluorotetracyano-p-quinodimethane (F₄TCNQ),trifluorotetracyano-p-quinodimethane (F₃TCNQ),difluorotetracyano-p-quinodimethane (F₂TCNQ),fluorotetracyano-p-quinodimethane (FTCNQ), dichloro dicyanoquinine(DDQ), o-chloranil and cyanil.

Further examples of suitable dopants include quinonediimine derivatives,including, e.g., those disclosed in U.S. Pat. No. 6,908,783 by Kuehl etal., which is incorporated by reference herein in its entirety.

Another class of dopants that can be used includes aminium salts.Aminium radical cations can be used as a redox additive to theformulation to undergo electron transfer. The byproducts formed need notnecessarily be removed from the composition, as they are also holetransporting moieties and are less likely to adversely affect transport.Examples of suitable aminium salts include, but are not limited to,tris-(4-bromophenyl)aminium hexachloroantimonate).

Other useful redox dopants include bora-tetraazapentalenes. Examples ofa bora-tetraazapentalene are represented by:

wherein R₁, R₂, R₃ are independently hydrogen, an optionally substitutedor unsubstituted alkyl, a heteroalkyl, an aryl, a heteroaryl, a fusedcarbocycle or a fused heterocycle group, and wherein independently R₄and R₅ are a halogen, hydrogen, an optionally substituted orunsubstituted alkyl, a heteroalkyl, an aryl, a heteroaryl, a fusedcarbocycle or fused heterocycle, or, together with the boron atom, aboron-containing heterocycle. (See, e.g., Rothe, Carsten, Laser andPhotonics Reviews (2007), 1(4), 303-306; and WO 2007115540 A1 (published2007 Oct. 18), and references therein.)

Another class of useful dopants is a silver salt, such as silvertetrafluoroborate, silver tetraphenylborate, silver hexafluorophosphate.Silver ions may undergo electron transfer to or from silver metal andthe conductive polymer salt. See, e.g., U.S. Pat. Nos. 5,853,906 and5,968,674.

In preparing the present compositions, the dopant is typicallyformulated first with the conductive polymer, to ensure that doping ofthe conducting polymer occurs. The semiconducting matrix component isthen added.

For example, in some embodiments, the composition is an ink formulationthat is prepared by combining the conductive conjugated polymer with thedopant to form a conductive polymer-dopant mixture. Typically, a stocksolution of the conductive conjugated polymer (e.g., one made bydissolving or dispersing the conductive polymer in an organic solvent)is combined with a stock solution of the dopant, to form apolymer-dopant solution. A stock solution of the semiconducting matrixcomponent is then added to the conducting polymer-dopant solution toform the ink formulation.

Alternatively, in some embodiments, the dopant is covalently attached tothe conductive conjugated polymer. In these embodiments, thecompositions are prepared by combining the conductive polymer-dopantwith the semiconducting matrix component to form the composition.

Amounts

The present compositions can comprise between about 1% and 99% by weight(“wt %,” or “% (w/w)”) of the conductive conjugated polymer, betweenabout 1% and 99% by weight of the semiconducting matrix component, and,if a dopant is present, between about 0% and 75% by weight dopant.Weight percentages for each component are calculated on the basis of theweight of all solids in the composition.

For example, in some embodiments, the compositions comprise about 10% toabout 90%, about 15% to about 80%, about 25% to about 75%, about 30% toabout 70%, or about 35% to about 65% by weight of the conductiveconjugated polymer with respect to the total amount of conductivepolymer, semiconducting matrix component, and dopant, if present.

In some embodiments, the compositions comprise about 10% to about 90%,about 15% to about 80%, about 25% to about 75%, about 30% to about 70%,or about 35% to about 65% by weight of the semiconducting matrixcomponent with respect to the total amount of conductive conjugatedpolymer, semiconducting matrix component, and dopant, if present. Inother embodiments, the compositions comprise about 10% to about 50%,about 10% to about 40%, about 10% to about 30%, or about 10% to about20% by weight of the semiconducting matrix component.

In some embodiments, the compositions comprise about 20% to about 80%,about 25% to about 75%, or about 25% to about 50%, by weight of thedopant with respect to the total amount of conductive conjugatedpolymer, semiconducting matrix component, and dopant. In thosecompositions in which a dopant is present, the amount by weight of theconductive polymer is generally greater than the amount by weight of thedopant.

In addition, the dopant can be present in an amount that corresponds tothe molar amount of repeat units of the conductive conjugated polymer.For example, the dopant is typically present in the composition in anamount of about 0.01 moles dopant/moles conductive polymer repeat unit(“m/ru”) to about 1 m/ru, wherein m is the molar amount of dopant and ruis the molar amount of conductive polymer repeat units. In someembodiments, the dopant is present in an amount of about 0.01 m/ru toabout 0.5 m/ru, about 0.1 m/ru to about 0.4 m/ru, or about 0.2 m/ru toabout 0.3 m/ru. Typically, the dopant is present in am amount of about0.2-0.3 m/ru.

In some embodiments, a dopant is not present in the composition.

Devices

The present compositions can be used to produce HILs or HTLs that can beincorporated into a number of organic electronic devices. HIL/HTL layerscan be prepared for these devices from the present compositions usingmethods known in the art, including, for example, solution or vacuumprocessing, as well as printing and patterning processes.

Examples of organic electronic devices that can be fabricated from thepresent compositions include, but are not limited to, OLEDs, PLEDs,PHOLEDs, SMOLEDs, ESDs, photovoltaic cells, as well as supercapacitors,hybrid capacitors, cation transducers, drug release devices,electrochromics, sensors, FETs, actuators, and membranes. Anotherapplication is as an electrode modifier including an electrode modifierfor an organic field effect transistor (OFETS). Other applicationsinclude those in the field of printed electronics, printed electronicsdevices, and roll-to-roll production processes. Additionally, thecompositions discussed herein may be a coating on an electrode.

Methods known in the art can be used to fabricate each of theseelectronic devices, in particular, for fabricating OLED and OPV devices.

For example, the present compositions can be used to form HILs for OLEDdevices. OLED devices are known in the art. See, for example, US PatentAppl. Publ. No. US 2006/00787661 A1, published Apr. 13, 2006. See alsoHammond et al., US Patent Appl. Publ. No. US 2006/0175582 A1, publishedAug. 10, 2006, entitled “Hole Injection/Transport Layer Compositions andDevices.” The devices can comprise, for example, multi-layer structuresthat include, for example, an anode, including a transparent conductorsuch as ITO on glass or PET or PEN; a hole injection layer; anelectroluminescent layer such as a polymer layer; a conditioning layersuch as LiF, and a cathode such as for example Ca, Al, or Ba. See alsoU.S. Pat. Nos. 4,356,429 and 4,539,507 (Kodak).

Materials for and methods of preparing each of these layers orcomponents are well known in the art. For example, conjugated polymerswhich emit light, for use in electroluminescent layers in OLEDS, aredescribed, for example, in U.S. Pat. Nos. 5,247,190 and 5,401,827(Cambridge Display Technologies). See also Kraft et al.,“Electroluminescent Conjugated Polymers-Seeing Polymers in a New Light,”Angew. Chem. Int. Ed., 1998, 37, 402-428, including device architecture,physical principles, solution processing, multilayering, blends, andmaterials synthesis and formulation, which is hereby incorporated byreference in its entirety. Light emitters known in the art andcommercially available can be used, including various conductingpolymers as well as organic molecules, such as materials available fromSumation, Merck Yellow, Merck Blue, American Dye Sources (ADS), Kodak(e.g, AlQ3 and the like), and even Aldrich such as BEHP-PPV. Suchpolymer and small-molecule materials are well known in the art and aredescribed in, for example, U.S. Pat. No. 5,047,687 issued to VanSlyke;and Bredas, J.-L., Silbey, R., eds., Conjugated Polymers, KluwerAcademic Press, Dordrecht (1991). See also “Organic Light-EmittingMaterials and Devices,” Z. Li and H. Meng, Eds., CRC Press (Taylor andFrancis Group, LLC), Boca Raton (2007), in particular, chapter 1 (pp.1-44), chapter 2 (pp. 45-294), chapter 3 (pp. 295-412), and chapter 10(pp. 617-638), for a fuller description of OLED components and layers.

Similarly, the present compositions can be used to form HTLs for organicphotovoltaic devices (OPVs). OPVs are known in the art. See, forexample, US Patent Publ. No. 2006/0076050, published Apr. 13, 2006; seealso WO 2008/018931, published Feb. 14, 2008, including descriptions ofOPV active layers. See also U.S. provisional Appl. No. 61/043,654, filedApr. 9, 2008, by Williams et al., entitled “Hole Collection LayerCompositions and Photovoltaic Devices,” which is herein incorporated byreference in its entirety. The devices can comprise, for example,multi-layer structures that include, for example, an anode, including atransparent conductor such as indium tin oxide (ITO) on glass or PET; ahole injection layer and/or a hole transport layer; a P/N bulkheterojunction layer; a conditioning layer such as LiF; and a cathodesuch as for example Ca, Al, or Ba. For example, a variety of photoactivelayers can be used in OPV devices. Photovoltaic devices can be preparedwith photoactive layers comprising fullerene derivatives mixed with, forexample, conducting polymers as described in for example U.S. Pat. Nos.5,454,880 (Univ. Cal.); 6,812,399; and 6,933,436. Also, photoactivelayers may comprise blends of conducting polymers, blends of conductingpolymers and semiconducting nanoparticles, and bilayers of smallmolecules such as phthalocyanines, fullerenes, and porphyrins.

Device Performance Measurements

The fabricated devices can be tested for device performance usingmethods known in the art. For example, for OLEDs, methods known in theart can be used to measure such device performance parameters asbrightness, efficiency, and lifetime.

Methods known in the art can be used to measure OLED performanceparameters. Device performance measurements are typically carried out at10 mA/cm². For example, the protocol outlined in Example 3 below is onemethod that can be used to measure OLED device performance parameters ofcurrent density (mA/cm²), operating voltage (V), brightness (cd/m²), andefficiency (cd/A).

Examples of typical OLED parameters are as follows:

Typical OLED device voltages can be, for example, from about 2 to about15, or about 2 to about 8, or about 2 to 5, or from about 3 to about 14,or from about 3 to about 7. Typical device brightness can be, forexample, at least 100 cd/m², or at least 500 cd/m², or at least 750cd/m², or at least 1,000 cd/m². Typical device efficiencies can be, forexample, at least 0.25 cd/A, or at least 0.45 cd/A, or at least 0.60cd/A, or at least 0.70 cd/A, or at least 1.00 cd/A, or at least 2.5cd/A, at least 4.00 cd/A, or at least 5.00 cd/A. Typical devicelifetimes can be measured at 50 mA/cm² or up to 75 mA/cm² in hours andcan be, for example, at least 50 hours, or at least 100 hours, or atleast about 900 hours, or at least 1,000 hours, or at least 1100 hours,or at least 2,000 hours, or at least 5,000 hours, or at least 10,000 h,or at least 20,000 h, or at least 50,000 h.

The present compositions, when used as HILs or HTLs in organic devices,typically lead to increases in device parameters such as powerefficiency. For example, in some embodiments, the present compositions,when used as HILs in OLEDs, can lead to increases in efficiency of atleast 5%, or at least about 10% or greater, up to about 50%, dependingon the operating voltage and quantum efficiency of the OLED in theabsence of a good hole injection layer, compared to OLEDs fabricatedusing traditional HILs that contain an insulating matrix component.

Additional embodiments are provided with a series of non-limitingworking examples.

WORKING EXAMPLES Example 1 Representative Formulations

A series of HIL ink formulations were prepared containing PDBEETh andIMDPIB(PhF₅)₄ as conductive conjugated polymer and dopant, and NPB assemiconducting matrix polymer, as shown in Table 1 below.

The ink formulations were obtained using the following generalprocedure: Separate stock solutions of PDBEETh and IMDPIB(PhF₅)₄ inCHCl₃ were first prepared, each containing 0.5% (w/w) solids. Variousamounts of each stock solution were combined as indicated in Table 1.For each formulation, the stock solution of IMDPIB(PhF₅)₄ was added tothe PDBEETh stock solution so that the moles of IMDPIB(PhF₅)₄ dopant perrepeat unit of the PDBEETh polymer was kept at 0.3. The resultingcombined solution was refluxed for 2 h under a nitrogen blanket andstored in the glove-box. The indicated weight percent of NPB (added as a0.5% (w/w) stock solution in chloroform) was added to the doped PDBEEThto prepare the final ink formulation.

TABLE 1 Composition of HILs containing the doped PDBEETh and NPB as thehole transporting matrix. Heating HIL # CHCl₃, % NPB, % PDBEETh, %IMDPIB(PhF₅)₄, % Temp. (° C.) Time (h) 1 99.5 0 0.285 0.215 reflux 2 299.5 0.125 0.213 0.162 reflux 2 3 99.5 0.25 0.142 0.108 reflux 2 4 99.50.375 0.071 0.054 reflux 2 5 99.5 0.5 0 0 — — % indicated are on weightbasis, with respect to total weight of the composition (%(w/w))

Films were made from the above formulations using procedures known inthe art. The films were annealed at 130° C. for 15 minutes and werecharacterized using UV-VIS-NIR spectroscopy. The solutions wereprepared, spun and annealed in a glove box.

FIG. 1 presents the UV-VIS-NIR spectra of the films made from the fiveHIL formulations in Table 1. The presence of the neutral NPB and dopedPDBEETh in each formulation are clearly shown.

Example 2 OLED Device Fabrication

OLED devices were fabricated following procedures known in the art. Thedevices were fabricated on indium tin oxide (ITO) surfaces deposited onglass substrates. The ITO surface was pre-patterned to define the pixelarea of 0.05 cm². The device substrates were cleaned by ultrasonicationin a dilute soap solution for 20 minutes followed by distilled waterwashes. This was followed by ultrasonication in isopropanol for 20minutes. The substrates were dried under nitrogen flow, followed bytreatment in a UV-Ozone chamber operating at 300 W for 20 minutes.

The cleaned substrates were then coated with an HIL ink formulation anddried at 90-170° C. for 5-15 minutes to form an HIL film layer. Dry filmthicknesses ranged from approximately 20 nm to 60 nm. The coatingprocess was done on a spin coater, but can be similarly achieved withspray coating, ink-jetting, contact printing, or any other depositionmethod capable of resulting in an HIL film of the desired thickness. Thesubstrates were then transferred to a vacuum chamber where the remaininglayers of the device stack were deposited by means of physical vapordeposition.

In this study, the HILs spun on top of the ITO surfaces included anexample of the invention (HIL #4 in Table 1 of Example 1 above) and acomparative benchmark (“Comparative HIL”). The Comparative HIL is anaqueous HIL layer made from an ink formulation having the followingcomposition:

Material Wt. % P3MEET-S 0.13 Poly(4-vinylphenol) 1.94Poly(styrenesulfonic acid) 0.07 Nafion 0.07 Water 53.79 Butyl Cellosolve44.01

The layers deposited on top of the HIL included a hole transportinglayer (HTL), an emissive layer (EML), a hole blocking layer (HBL), anelectron transporting layer (ETL), and a metal cathode. The materialsused were N,N′(dinaphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB) as theHTL, bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-biphenyl-4-olato)aluminum(BAlq) doped with tris-(1-phenylisoquinoline)iridium III (Ir(piq)₃) forthe EML, BAlq as the HBL, and tris(8-hydroxyquinoline)aluminium (Alq3)as the ETL. All of these materials are commercially available andtypically found in OLED structures in the art. The cathode layer wasprepared by the sequential deposition of two metal layers, the firstbeing a 3 nm to 5 nm layer of Ca (0.1 nm/sec) followed by a 200 nm layerof Al (0.5 nm/sec) with the base pressure at 5×10⁻⁷ Torr.

The devices thus obtained were encapsulated with a glass cover slip toprevent exposure to ambient conditions by means of a UV-light curingepoxy resin cured at 80 W/cm² UV exposure for 4 minutes.

Example 3 OLED Device Testing

Performance tests were conducted on the OLED devices of Example 2.Typically, performance is quantified by a combination of differentparameters such as operating voltage (should be low), brightness in nits(should be bright, luminous), efficiency in units of cd/A (reflectinghow much electric charge is needed to obtain light from the device), andthe lifetime under operation (time required to reach half of the initialluminance value at the start of the test). As such, the overallperformance is very important in a comparative evaluation of HILperformance. Performance of the devices was tested using the using thefollowing procedures.

The OLED devices comprise pixels on a glass substrate whose electrodesextend outside the encapsulated area of the device which contain thelight emitting portion of the pixels. The typical area of each pixel insuch devices is 0.05 cm². To test the devices, the electrodes werecontacted with a current source meter such as a Keithley 2400 sourcemeter with a bias applied to the indium tin oxide electrode while thealuminum electrode is earthed. This procedure results in positivelycharged carriers (holes) and negatively charged carriers being injectedinto the device which form excitons and generate light. In the OLEDdevices of this example, the HIL layer of the device assists theinjection of charge carriers into the light emitting layer, resulting ina low operating voltage of the device (defined as the voltage requiredto run a given current density through the pixel).

Simultaneously, another Keithley 2400 source meter was used to address alarge area silicon photodiode. This photodiode was maintained at zerovolts bias by the 2400 source meter and placed in direct contact witharea of the glass substrate directly below the lighted area of the OLEDpixel. The photodiode is used to collect the light generated by the OLEDdevice, converting it into photocurrent which is in turn read by thesource meter. The photodiode current generated is quantified intooptical units (candelas/sq. meter) by calibrating it with the help of aMinolta CS-200 Chromameter.

Voltage-current-light or IVL data for the OLED pixels of the deviceswere generated as follows: During the testing of the device, theKeithley 2400 source meter addressing the OLED pixel applied a voltagesweep to it. The resultant current passing through the pixel wasmeasured. At the same time, the current passing through the OLED pixelresulted in light being generated, which then resulted in a photocurrentreading by the other Keithley 2400 source meter connected to thephotodiode. This in turn enabled the measurement of other devicecharacteristics, such as the lumens per Watt of electrical input powerto the pixel (power efficiency) and candelas per ampere of pixelcurrent.

Current density (mA/cm²), operating voltage (V), brightness (cd/m²), andefficiency (cd/A) were measured for the OLED devices of Example 2containing an Inventive HIL and a comparative HIL The results arepresented in Table 2. The Inventive HIL was made using the HIL inkformulation #4 of Example 1. The Comparative HIL was made as describedabove in Example 2. Devices containing the inventive HIL producedgreater brightness and higher efficiency than those containing thecomparative HIL.

TABLE 2 Current Density Voltage Brightness Efficiency HIL System Devicestructure (mA/cm²) (V) (cd/m²) (cd/A) ComparativeITO/HIL/NPB/BAlq:Ir(plq)3 30 9.95 1180 3.9 HIL (15 wt %)/BAlq/Alq3/Ca/AlInventive 30 12.6 1270 4.3 HIL

OLED devices can also be tested for their lifetime performance. Lifetimeperformance is measured using lifetime testers where a constant currentis sourced through the tested devices. The current to the device isadjusted so that it gives a certain initial luminance value. Forlifetime performance tests, this value is typically set at 1,000candela/meter². The luminance decay and voltage rise over time are thennoted.

OLED devices fabricated in a manner similar to those of Example 2 abovewere tested for lifetime performance. The OLED devices contained theComparative HIL and Inventive HIL used for the device efficiencymeasurements shown in Table 2, and had the general structureITO/HIL/NPB/BAlq:Ir(piq)₃ (15 wt %)/E246/EI-101/A (where E246 refers toan electron transport layer, and EI-101 refers to an electron injectionlayer, available from OLED-T Ltd., Enfield, UK) The results of thelifetime performance tests are shown in Table 3. Devices containing theinventive HIL produced greater brightness and longer lifetimes thanthose containing the comparative HIL.

TABLE 3 Brightness Lifetime (cd/m²) (time to 50% under of beginning HILSystem Device structure lifetest luminance) ComparativeITO/HIL/NPB/BAlq:Ir(piq)3 1,000  10¹ HIL (15 wt %)/E246/EI-101/AlInventive 2,000 713¹ HIL ¹at 2,000 nits

1-53. (canceled)
 54. An ink composition comprising: (i) at least oneconductive conjugated polymer, wherein the conductive conjugated polymeris a doped polythiophene; (ii) at least one semiconducting matrixcomponent different from the conductive conjugated polymer, wherein thesemiconducting matrix component is a hole-transporting material; (iii)at least one organic solvent; and (iv) wherein the ink compositioncomprises less than 5% (w/w) of an insulating matrix component.
 55. Theink composition according to claim 54, wherein the ink compositioncomprises less than 3% (w/w) of an insulating matrix component.
 56. Theink composition according to claim 54, wherein the ink compositioncomprises less than 1% (w/w) of an insulating matrix component.
 57. Theink composition according to claim 54, wherein the conductive conjugatedpolymer has a band gap of less than 1 eV, wherein the semiconductingmatrix component has a band gap of 1-3 eV, and wherein insulating matrixcomponent has a band gap of more than 3 eV.
 58. The ink compositionaccording to claim 54, wherein the semiconducting matrix component is ahole-transporting polymer.
 59. The ink composition according to claim54, wherein the semiconducting matrix component is a hole-transportingsmall molecule.
 60. The ink composition according to claim 54, whereinthe semiconducting matrix component is substantially undoped in the inkcomposition.
 61. The ink composition according to claim 54, wherein theconductive conjugated polymer is doped by a redox dopant.
 62. The inkcomposition according to claim 54, wherein the ink composition issubstantially free of polystyrene sulfonic acid and nafion.
 63. The inkcomposition according to claim 54, wherein the ink composition issubstantially free of water.
 64. An OLED device comprising ahole-injection layer, said hole-injection layer comprising: (i) at leastone conductive conjugated polymer, wherein the conductive conjugatedpolymer is a doped polythiophene; (ii) at least one semiconductingmatrix component different from the conductive conjugated polymer,wherein the semiconducting matrix component is a hole-transportingmaterial; and (iii) wherein the hole-injection layer comprises less than5% (w/w) of an insulating matrix component.
 65. The OLED deviceaccording to claim 64, wherein the hole-injection layer comprises lessthan 3% (w/w) of an insulating matrix component.
 66. The OLED deviceaccording to claim 64, wherein the hole-injection layer comprises lessthan 1% (w/w) of an insulating matrix component.
 67. The OLED deviceaccording to claim 64, wherein the semiconducting matrix component isdoped and is in admixture with the conductive conjugated polymer. 68.The OLED device according to claim 64, wherein the semiconducting matrixcomponent is undoped and is in admixture with the conductive conjugatedpolymer.
 69. The OLED device according to claim 64, wherein chargeinjection takes place within the bulk of the hole-injection layer. 70.The OLED device according to claim 64, wherein the conductive conjugatedpolymer has a band gap of less than 1 eV, wherein the semiconductingmatrix component has a band gap of 1-3 eV, and wherein insulating matrixcomponent has a band gap of more than 3 eV.
 71. The OLED deviceaccording to claim 64, wherein the hole-injection layer has a thicknessof 60-200 nm and is substantially transparent to visible light.
 72. TheOLED device according to claim 64, wherein the hole-injection layer issubstantially free of polystyrene sulfonic acid and nafion.
 73. Amethod, comprising: (a) providing a first composition comprisingconductive conjugated polymer, wherein the conductive conjugated polymeris a doped polythiophene; (b) adding a second composition to the firstcomposition to form a third composition, wherein the second compositioncomprises a semiconducting matrix component different from theconductive conjugated polymer, wherein the semiconducting matrixcomponent is a hole-transporting material, and wherein the thirdcomposition comprises less than 5% (w/w) of an insulating matrixcomponent; (c) cast the third composition into a film.